A method for preparing heat-insulating expanded polystyrene particles

Abstract

The invention discloses a method for preparing heat-insulating expanded polystyrene particles, belongs to the technical field of foaming materials, and comprises the following steps: weighing raw materials according to the following weight parts: 100 parts of polystyrene, 8-10 parts of modified silica, 2-3 parts of smoke suppressant, and 5-6 parts of foaming agent; after all the raw materials are mixed, they are mixed for 10 minutes using a high-speed mixer, and granulated using a twin-screw extruder; after granulation is completed, a single-screw extruder is used for foaming and extrusion to obtain expanded polystyrene particles. The present invention adds modified silica to the raw materials, and the modified silica is a hollow silica microsphere with an organic molecular chain grafted on the surface, so that excellent heat insulation effect can be achieved by adding a small amount of silica; in addition, the molecular chain structure grafted on the surface contains a phosphate group, which belongs to a flame retardant component, and is introduced into polystyrene with nano-silicon dioxide, which can effectively improve the flame retardant properties of polystyrene and expand the application range of expanded polystyrene.

Description

Technical Field

[0001] The invention belongs to the technical field of foaming materials, and in particular relates to a method for preparing heat-insulating foamed polystyrene particles. Background Art

[0002] Polystyrene foam has excellent productivity, light weight and low price, and is widely used as a thermal insulation material for buildings. When the thermal insulation performance of polystyrene foam is improved, energy can be reduced, and the density and thickness are reduced to reduce the amount of polystyrene used, which not only reduces manufacturing costs but also has the advantage of increasing living space. Therefore, improving the thermal insulation of polystyrene foam is a research hotspot.

[0003] In addition, polystyrene foam materials have poor flame retardancy, and there are hidden dangers such as easy ignition and easy dripping. When used as building insulation materials, there are fire safety hazards. There are also existing technologies that add halogen-containing flame retardants to improve their flame retardant properties. Halogen-containing flame retardants will release toxic substances during combustion or heating, which does not meet environmental protection requirements. In view of the fact that ordinary polystyrene foam materials do not have flame retardant functions and the environmental disadvantages of halogen-containing flame retardants in flame retardant polystyrene materials, it is imperative to develop an environmentally friendly, efficient and new type of polystyrene foam material. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a method for preparing heat-insulating expanded polystyrene particles.

[0005] In order to improve the thermal insulation performance of polystyrene foam material, the present invention adds modified silica to the raw material, and the modified silica is hollow silica microspheres with organic molecular chains grafted on the surface. The hollow silica microspheres not only have strong infrared reflection characteristics, but also the porous structure of the hollow microspheres can increase the restriction on the thermal motion of air molecules, thereby further improving the thermal insulation effect. The organic molecular chain structure grafted on the surface contains a benzene ring structure, which has high compatibility with the polystyrene matrix, can improve the interface bonding force between silica and the matrix, promote the uniform dispersion of the hollow silica microspheres in the matrix, enable it to better play the role of thermal insulation and mechanical performance enhancement, and achieve excellent thermal insulation effect with a small amount of addition; in addition, the molecular chain structure grafted on the surface contains phosphate groups, which are flame retardant components. Introducing them into polystyrene along with nano-silicon dioxide can effectively improve the flame retardant properties of polystyrene and expand the application range of foamed polystyrene.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing heat-insulating expanded polystyrene particles comprises the following steps:

[0008] The first step is to weigh the raw materials according to the following weight parts: 100 parts of polystyrene, 8-10 parts of modified silicon dioxide, 2-3 parts of smoke suppressant, and 5-6 parts of foaming agent;

[0009] Step 2: After all the raw materials are mixed, they are mixed in a high-speed mixer for 10 minutes, and granulated using a twin-screw extruder. The temperature of heating zone I-heating zone II is set at 150-155°C, the temperature of heating zone III-heating zone IV is set at 155-160°C, and the temperature of heating zone V-heating zone VI is set at 160-165°C;

[0010] The third step is to complete the granulation and use a single screw extruder for foaming extrusion. The temperature of the feeding section and the compression section is 150-155°C, the temperature of the homogenization section is 165-175°C, and the temperature of the die is 140-145°C to obtain foamed polystyrene particles.

[0011] Furthermore, the smoke suppressant is a mixture of one or more of zinc borate, ferrocene, organosilicon, aluminum hydroxide, molybdenum trioxide or ammonium molybdate in any proportion.

[0012] Furthermore, the modified silicon dioxide is prepared by the following steps:

[0013] S1. Anhydrous ethanol was used as the reaction medium, and a polystyrene emulsion (solid content was 60 g / L) was added, and then a silane coupling agent KH560 was added to combine with the surface of the polystyrene particles to form a hydrophilic group, and the polystyrene particles were fully stirred to disperse evenly, and the pH value was adjusted to 10 with ammonia water, and then the reaction temperature was increased to 50°C, and tetraethyl silicate was added dropwise, and the reaction was carried out for 3 hours to obtain a polystyrene-silica microsphere composite emulsion, which was washed with pure water and ethanol several times, and dried in a drying oven to obtain composite microspheres, and calcined at 450°C to obtain hollow silica microspheres; the amount ratio of anhydrous ethanol, polystyrene emulsion, silane coupling agent KH560, and tetraethyl silicate was 100 mL: 50 mL: 1 mL: 7.5 mL;

[0014] Using polystyrene as a hard template, after hydrothermal precipitation and high-temperature calcination, hollow silica microspheres are obtained; compared with ordinary nano-silica, hollow silica microspheres not only have strong infrared reflection properties, but also the porous structure of the hollow microspheres can increase the restriction on the thermal motion of air molecules, thereby further improving the thermal insulation effect;

[0015] S2, the silane coupling agent KH550 and ethanol are fully mixed, the hollow silica microspheres are added to the solution, and the mixture is placed in a high-speed mixer for high-speed mixing, the mixing temperature is 80° C., the mixing time is 20-25 min, and finally the mixture is dried in a blast dryer at 105° C. for 4 h to obtain pre-modified silica; the ratio of the amount of silane coupling agent KH550, ethanol and hollow silica microspheres is 5g:20mL:40g;

[0016] The hollow silica microspheres are surface treated by using silane coupling agent KH550, and the molecular chains of silane coupling agent KH550 are grafted on the surface;

[0017] S3. Under nitrogen protection, pre-modified silica, 2-carboxyethylphenylphosphite, triethylamine and dichloromethane were added to a round-bottom flask, and then DIC (N,N-diisopropylcarbodiimide) was added. The mixture was stirred and reacted for 3 hours at room temperature under N2 protection. After the reaction was completed, the mixture was centrifuged and washed with ethanol and deionized water for 3-4 times in sequence. Finally, the filter cake was placed in an 80°C drying oven and dried to constant weight, ground and sieved to obtain modified silica. The ratio of pre-modified silica, 2-carboxyethylphenylphosphite, triethylamine, DIC and dichloromethane was 5g:21.4g:10.1g:6.3g:300mL.

[0018] Under the action of DIC and triethylamine, -NH2 on the surface of pre-modified silica reacts chemically with -COOH on the 2-carboxyethylphenylphosphite molecule to obtain modified silica;

[0019]

[0020] The modified silica obtained is hollow silica microspheres with organic molecular chains grafted on the surface. The hollow silica microspheres not only have strong infrared reflection characteristics, but also the porous structure of the hollow microspheres can increase the restriction on the thermal motion of air molecules, thereby further improving the thermal insulation effect. The surface-grafted organic molecular chain structure contains a benzene ring structure, which has a high compatibility with the polystyrene matrix, can improve the interfacial bonding force between silica and the matrix, and promote the uniform dispersion of the hollow silica microspheres in the matrix, so that it can better play a role in thermal insulation and mechanical property enhancement, and achieve excellent thermal insulation effect with a small amount of addition; in addition, the molecular chain structure grafted on the surface contains phosphate groups, which are flame retardant components. Introducing them into polystyrene along with nano-silica can not only effectively improve the flame retardant properties of polystyrene, but also, compared with the direct addition of small molecules, can prevent the occurrence of easy migration and seepage, which affects the realization of flame retardant effects.

[0021] Beneficial effects of the present invention:

[0022] In order to improve the thermal insulation performance of polystyrene foam material, the present invention adds modified silica to the raw material, and the modified silica is hollow silica microspheres with organic molecular chains grafted on the surface. The hollow silica microspheres not only have strong infrared reflection characteristics, but also the porous structure of the hollow microspheres can increase the restriction on the thermal motion of air molecules, thereby further improving the thermal insulation effect. The organic molecular chain structure grafted on the surface contains a benzene ring structure, which has high compatibility with the polystyrene matrix, can improve the interface bonding force between silica and the matrix, promote the uniform dispersion of the hollow silica microspheres in the matrix, enable it to better play the role of thermal insulation and mechanical performance enhancement, and achieve excellent thermal insulation effect with a small amount of addition; in addition, the molecular chain structure grafted on the surface contains phosphate groups, which are flame retardant components. Introducing them into polystyrene along with nano-silicon dioxide can effectively improve the flame retardant properties of polystyrene and expand the application range of foamed polystyrene. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1

[0025] Preparation of modified silica:

[0026] S1. Use 100 mL of anhydrous ethanol as the reaction medium, add 50 mL of polystyrene emulsion (solid content is 60 g / L), and then add 1 mL of silane coupling agent KH560 to combine with the surface of polystyrene particles to form hydrophilic groups, stir well to make the polystyrene particles dispersed evenly, adjust the pH value to 10 with ammonia water, then increase the reaction temperature to 50°C, add 7.5 mL of tetraethyl silicate dropwise, react for 3 hours, obtain polystyrene-silica microsphere composite emulsion, wash with pure water and ethanol three times successively, dry in a drying oven to obtain composite microspheres, and calcine at 450°C to obtain hollow silica microspheres;

[0027] S2, 5g of silane coupling agent KH550 and 20mL of ethanol were fully mixed, 40g of hollow silica microspheres were added to the solution, and the mixture was placed in a high-speed mixer for high-speed mixing at a mixing temperature of 80°C and a mixing time of 20min. Finally, the mixture was dried in a blast dryer at 105°C for 4h to obtain pre-modified silica;

[0028] S3. Under nitrogen protection, add 5 g of pre-modified silica, 21.4 g of 2-carboxyethylphenylphosphorous acid, 10.1 g of triethylamine and 300 mL of dichloromethane into a round-bottom flask, and then add 6.3 g of DIC (N,N-diisopropylcarbodiimide). Stir and react for 3 hours at room temperature under N2 protection. After the reaction is completed, centrifuge and wash with ethanol and deionized water for 3 times in sequence. Finally, put the filter cake into an 80°C drying oven and dry it to constant weight, grind and sieve to obtain modified silica.

[0029] Example 2

[0030] Preparation of modified silica:

[0031] S1, using 200mL of anhydrous ethanol as a reaction medium, adding 100mL of polystyrene emulsion (solid content of 60g / L), and then adding 2mL of silane coupling agent KH560 to combine with the surface of polystyrene particles to form hydrophilic groups, stirring fully to disperse the polystyrene particles evenly, adjusting the pH value to 10 with ammonia water, then increasing the reaction temperature to 50°C, adding 15mL of tetraethyl silicate dropwise, reacting for 3h, obtaining a polystyrene-silica microsphere composite emulsion, washing with pure water and ethanol four times in succession, drying in a drying oven to obtain composite microspheres, and calcining at 450°C to obtain hollow silica microspheres;

[0032] S2, 10g of silane coupling agent KH550 and 40mL of ethanol were fully mixed, 80g of hollow silica microspheres were added to the solution, and the mixture was placed in a high-speed mixer for high-speed mixing at a mixing temperature of 80°C and a mixing time of 25min. Finally, the mixture was dried in a blast dryer at 105°C for 4h to obtain pre-modified silica;

[0033] S3. Under nitrogen protection, add 10g of pre-modified silica, 42.8g of 2-carboxyethylphenylphosphorous acid, 20.2g of triethylamine and 600mL of dichloromethane into a round-bottom flask, and then add 12.6g of DIC (N,N-diisopropylcarbodiimide). Stir and react for 3h at room temperature under N2 protection. After the reaction is completed, centrifuge and wash with ethanol and deionized water for 4 times in sequence. Finally, put the filter cake into an 80℃ drying oven and dry it to constant weight, grind and sieve to obtain modified silica.

[0034] Example 3

[0035] A method for preparing heat-insulating expanded polystyrene particles comprises the following steps:

[0036] Step 1: weigh the raw materials according to the following weight parts: 100 g of polystyrene, 8 g of modified silicon dioxide obtained in Example 1, 2 g of zinc borate, and 5 g of foaming agent;

[0037] Step 2: After all the raw materials are mixed, they are mixed in a high-speed mixer for 10 minutes, and granulated using a twin-screw extruder. The temperature of heating zone I-heating zone II is set to 150°C, the temperature of heating zone III-heating zone IV is set to 155°C, and the temperature of heating zone V-heating zone VI is set to 160°C;

[0038] The third step is to complete the granulation and use a single-screw extruder for foaming extrusion. The temperature of the feeding section and the compression section is 150°C, the temperature of the homogenization section is 165°C, and the temperature of the die is 140°C to obtain foamed polystyrene particles.

[0039] Example 4

[0040] A method for preparing heat-insulating expanded polystyrene particles comprises the following steps:

[0041] Step 1: weigh the raw materials according to the following weight parts: 100 g of polystyrene, 9 g of modified silica prepared in Example 2, 2.5 g of ferrocene, and 5.5 g of foaming agent;

[0042] Step 2: After all the raw materials are mixed, they are mixed in a high-speed mixer for 10 minutes, and granulated using a twin-screw extruder. The temperature of heating zone I-heating zone II is set to 153°C, the temperature of heating zone III-heating zone IV is set to 158°C, and the temperature of heating zone V-heating zone VI is set to 163°C;

[0043] In the third step, after granulation is completed, a single-screw extruder is used for foaming extrusion. The temperature of the feeding section and the compression section is 153° C., the temperature of the homogenizing section is 170° C., and the temperature of the die is 143° C. to obtain foamed polystyrene particles.

[0044] Example 5

[0045] A method for preparing heat-insulating expanded polystyrene particles comprises the following steps:

[0046] Step 1: weigh the raw materials according to the following weight parts: 100 g of polystyrene, 10 g of modified silicon dioxide obtained in Example 1, 3 g of ammonium molybdate, and 6 g of foaming agent;

[0047] Step 2: After all the raw materials are mixed, they are mixed in a high-speed mixer for 10 minutes, and granulated using a twin-screw extruder. The temperature of heating zone I-heating zone II is set to 155°C, the temperature of heating zone III-heating zone IV is set to 160°C, and the temperature of heating zone V-heating zone VI is set to 165°C;

[0048] The third step is to complete the granulation and use a single-screw extruder for foaming extrusion. The temperature of the feeding section and the compression section is 155°C, the temperature of the homogenization section is 175°C, and the temperature of the die is 145°C to obtain foamed polystyrene particles.

[0049] Comparative Example

[0050] The modified silicon dioxide in Example 3 was replaced with ordinary silicon dioxide, and the other raw materials and preparation process remained unchanged.

[0051] The expanded polystyrene particles obtained in Examples 3-5 were processed into test specimens and subjected to the following performance tests:

[0052] Compressive strength: Use universal mechanical testing machine to test 10% compressive strength;

[0053] Thermal conductivity test: Tested according to GB / T 10294-2008;

[0054] Flame retardant performance test: LOI is tested according to GB / T 2408-2008; smoke production (TSP) is tested according to ISO5660-1;

[0055] The measured results are shown in the following table:

[0056] Example 3 Example 4 Example 5 Comparative Example 10% compressive strength / KPa 139 143 142 122 <![CDATA[Thermal conductivity / W·m -1 ·K -1 > 0.0307 0.0301 0.0305 0.0391 LOI / % 35.8 36.4 36.1 25.3 <![CDATA[Smoke production amount / m 2 > 410.8 420.5 416.2 450.8

[0057] It can be seen from the data in the above table that the polystyrene foam material obtained by the present invention has a compressive strength that meets the requirements and a low thermal conductivity, indicating that it has excellent thermal insulation performance; it has a LOI coefficient greater than 35% and a low smoke production, indicating that it has high flame retardant properties; combined with the data of the comparative example, it can be seen that the modified silica of the present invention can not only improve the thermal insulation performance, but also give polystyrene good flame retardant properties.

[0058] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0059] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for preparing heat-insulating expanded polystyrene particles, characterized in that: The steps include: The first step is to weigh the raw materials according to the following weight parts: 100 parts of polystyrene, 8-10 parts of modified silicon dioxide, 2-3 parts of smoke suppressant, and 5-6 parts of foaming agent; The second step is to mix all the raw materials, use a high-speed mixer to mix for 10 minutes, and use a twin-screw extruder to granulate; The third step is to complete the granulation and use a single screw extruder for foaming and extrusion to obtain expanded polystyrene particles; Wherein, the modified silicon dioxide is prepared by the following steps: S1. Use anhydrous ethanol as the reaction medium, add polystyrene emulsion, then add silane coupling agent KH560, stir well to make the polystyrene particles dispersed evenly, adjust the pH value to 10 with ammonia water, then increase the reaction temperature to 50°C, add tetraethyl silicate dropwise, react for 3 hours to obtain polystyrene-silica microsphere composite emulsion, wash with pure water and ethanol several times, dry in a drying oven to obtain composite microspheres, and calcine at 450°C to obtain hollow silica microspheres; S2, the silane coupling agent KH550 and ethanol are fully mixed, the hollow silica microspheres are added to the solution, and the mixture is placed in a high-speed mixer for high-speed mixing at a mixing temperature of 80° C. and a mixing time of 20-25 min. Finally, the mixture is dried in a blast dryer at 105° C. for 4 h to obtain pre-modified silica; S3. Under nitrogen protection, pre-modified silica, 2-carboxyethylphenylphosphite, triethylamine and dichloromethane were added to a round-bottom flask, and then N,N-diisopropylcarbodiimide was added. The mixture was stirred and reacted for 3 hours at room temperature under N2 protection. After the reaction was completed, the mixture was centrifuged and washed with ethanol and deionized water for 3-4 times in sequence. Finally, the filter cake was placed in an 80°C drying oven and dried to constant weight, and then ground and sieved to obtain modified silica.

2. The method for preparing heat-insulating expanded polystyrene particles according to claim 1, characterized in that: In the second step, the temperature of heating zone I-heating zone II is set to 150-155°C, the temperature of heating zone III-heating zone IV is set to 155-160°C, and the temperature of heating zone V-heating zone VI is set to 160-165°C.

3. The method for preparing heat-insulating expanded polystyrene particles according to claim 1, characterized in that: In the third step, the temperature of the feeding section and the compression section is 150-155°C, the temperature of the homogenization section is 165-175°C, and the temperature of the die is 140-145°C.

4. The method for preparing heat-insulating expanded polystyrene particles according to claim 1, characterized in that: The smoke suppressant is a mixture of one or more of zinc borate, ferrocene, organosilicon, aluminum hydroxide, molybdenum trioxide or ammonium molybdate in any proportion.

5. The method for preparing heat-insulating expanded polystyrene particles according to claim 1, characterized in that: In step S1, the ratio of anhydrous ethanol, polystyrene emulsion, silane coupling agent KH560, and tetraethyl silicate is 100 mL: 50 mL: 1 mL: 7.5 mL, and the solid content of the polystyrene emulsion is 60 g / L.

6. The method for preparing heat-insulating expanded polystyrene particles according to claim 1, characterized in that: In step S2, the ratio of the amount of silane coupling agent KH550, ethanol and hollow silica microspheres is 5g:20mL:40g.

7. The method for preparing heat-insulating expanded polystyrene particles according to claim 1, characterized in that: In step S3, the ratio of the amount of pre-modified silica, 2-carboxyethylphenylphosphorous acid, triethylamine, N,N-diisopropylcarbodiimide and dichloromethane is 5g:21.4g:10.1g:6.3g:300mL.

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